Process for hydrogenating aldehydes



Aug. 28, 1956 B. H. GWYNN PRocEssFoR HYDROGENATING ALDEHYDES Filed Dec.30, 1950 6 n n t oa I u Q o no ivm@ Mm. WH.

nited States Patent' i PROCESS FOR HYDRGENATING -ALDEHYDES Bernard H.Gwynn, Fawn Township, Alleghenyk County,

Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., acorporation of Delaware Application December 30, 1950, Serial No.203,588

7 claims. (Cl. 26o-638) This invention relates to a process forhydrogenating aldehydes and more particularly, to a process forpreferentially hydrogenating aldehydes in a mixture containing aldehydesand olens.

Olens are hydroformylated in the iirSt, or hydroformylating, stage ofthe Oxo process. in this stage, which is also known as the oxonation orcarbonylation stage, olens react with carbon monoxide and hydrogen toproduce aldehydes. Other organic reaction products such as alcohols andacetals are also produced. The product stream from the hydroformylationstage contains aldehydes, other reaction products, and in additionunreacted oletins, carbon monoxide, and hydrogen.

ln the second, or hydrogenation stage of the Oxo process, aldehydes froma hydroformylation stage are converted to alcohols and other oxygenatedproducts are also produced. However, in the previously proposedprocesses of which I am aware for hydrogenating aldehydes to alcohols ina mixture which also contains oletins, an important proportion of theolens has been hydrogenated to paraflins, thus producing a mixture ofhydrocarbons or a hydrocarbon fraction of the hydrogenation productsconsisting of a relatively smaller 'amount of unconverted olefins and arelatively larger amount of paraiins. It is desirable to prevent thisconversion of olefins to parains in the Ihydrocarbon frac- 'tion becauseif the oleins in this fraction are not hydrogenated the efficiency ofthe Oxo process can be improved by recovering the olefns from thehydrogenation stage products and using them as such or recycling them.My invention is concerned with a process for preferentiallyhydrogenating aldehydes in the presence of oletins while employingconventional hydrogenation pressures such as -100 to 1,000 pounds persquare inch.

I have found that aldehydes mixed with olens can be hydrogenated toalcohols while a hydrocarbon fraction can be produced which consistschiefly of olens by introducing water into a -mixturevof aldehydes andolens, and then hydrogenating the resulting mixture in the presence ofthe added water over a catalyst efective at low temperatures, forexample, temperatures below 500 F.' When operating in this manner,aldehydes are converted to alcohols and a hydrocarbon fractionconsisting chiefly of olens is produced. The oletins can readily beseparated from the alcohols and recycledto a lhydroformylation stage.

I have found that it is important to carry out the process at arelatively low temperature as otherwise thev olens are hydrogenatedalong with the aldehydes. Concomitantly, it is important to use acatalyst which is an eifective 'hydrogenationcatalyst at lowtemperatures because when operating at a low temperature with a catalystwhich exhibits maximum activity at a high temperature of, `for example,800 to 1,000 F.,.very little hydrogenation of either aldehydes oroletins occurs. On the other hand, when attempting tooperate at hightemperatures using a high temperature catalyst, the eifect of thetemperature so overbalances the effect of the added water that thehydrogenation of the olens is not substantially prevented. As statedabove, the present process is carried out at temperatures below l500 F.Preferred results Yare obtained at temperatures below 450 ice F.; forexample, temperatures in the range of about 300 to about 450 F. andparticularly in the range of about 350 to about'400" F.

With respect tothe catalysts that can be employed, in general anycatalyst eiective at low temperatures will be suitable for use. Theso-called low temperature hydrogenation catalysts are well known in theart and only a few are mentioned by wayA of example. Preferred catalysts'are nickel, cobalt, nickel tungsten sulde, cobalt molybdate, yandcopper chromite catalysts. The catalyst' can be in pelleted orgranulated form and can be placed in the.hydroge'nation zone as such. Ingeneral, however,` preferred results are obtained when the catalyst isdeposited upon a carrier such as diatornaceous earth or kieselguhr.

The water can beintroduced in liquid or vapor phase to the mixture 4lofaldehydes and oletins before or after the mixture is' introduced to thehydrogenation stage. Usually when hydrogenation is carried out at anelevated pressure such as at 1,000 pounds per square inch, it is moreconvenient to introduce water in liquid phase and to heat the mixture ofihydroformylation products and water to the desired hydrogenationtemperature. Part of the watercan be introduced at room temperature inliquid phase into the hydrogenation reactor at intervals along thedirection 'of flow in the reactor. ln this way the temperature in the"reactorcan be controlled because the heatv of hydrogenation isdissipated in vaporizing and heating vthe lwater to/ the hydrogenationtemperature.

The mixture of 'aldehydes'and oleins which is preferentiallylhydrogen'ated yin accordance with the process of-my invention canb'e'obtained in a number of ways, but usually it 1i's'cbtz'iined bylremovingcarbon monoxide 'andy hydrogen `andcaltaly'tic metals from aproduct stream obtained 4from a hydroformylation stage of an 'Oxoprocess. yThe mixture will therefore be identiied hereafter ashyd'r'oformylation products.

' The amount' of water Achargediwith the hydroformylationproduct's'td'th'ehydrogenation zone can be Varied. It is preferably"Lto-use as small an amount of water as 'possible `and'stil-lointain theadvantages of my invention "embo'diinetfwill -nwbedescribed inconnection with the accompanying drawing. The single figure shows aschematic representation 'of` asuitable plant system for carrying outthe 'proeess of my 'in'veniton A 'synthesis mixture of carbon monoxideand hydrogen yis introduced by iline 23, yand a mixture of oleiins and ahydroformyla'tion catalyst, usually an iron or cobalt catalyst'by'line4, to hydro'fo'r-rylation stage 6. The oleins and the synthesis gas-arereacted and the catalytic metal salts or carbonyls are removed.Hydroforrnylation products containing aldehydes, other reactionproducts, andunreactedlolelihsfat a pressure of about 500 pounds persquare inch'and -a l'temperature of about 150 F. areremovedfromzhydroformylation stage 6 by line 7. Water isintroducedfbyline '8 to vpump 9 and is then introduced at apressur'efoff-about '500 pounds per square inch into thehydroform'ylation''products by line 11. The resultng mixtureof rwaterand hydroformylation products is passed byline 12.l through heatexchanger 13 wherein the mixture is heated t'o la temperature of about400 F. The heated mixture is the'n passed-from heat exchanger i3 by line14"-to hydrogenation reactor 16. The hydrogenation reactor 16 contains anumber of baskets, 17a to lf, which are packed with 1r-inch nickel onkiesclguhr catalyst pellets 16. The pellets which contain about 44 percent nickel in their original state may be used as the oxide aftercalcining or may be partially reduced at 900 F. by passing hydrogen overthem for four hours at atmospheric pressure at the rate of about 635volumes of hydrogen per hour per volume of catalyst.

After the catalyst is prepared, hydrogen at a pressure of about 500pounds per square inch is passed by line 19 to heat exchanger 20 inwhich it is heated to a temperature of about 400 F. The heated hydrogenis introduced by line 21 to the top of hydrogenation reactor 16. Themixture of hydroformylation products, water, and hydrogen passesdownwardly through the hydrogenation reactor 16. the aldehydes in thehydrogenation reactor reacting with hydrogen to produce alcohols.

Additional hydrogen at a pressure of about 500 pounds per square inchand a temperature of about 100 F. is introduced beneath the catalystbaskets in the hydrogenation reactor from the hydrogen inlet line 19 byline 22 and a parallel system of valved lines, 23a to 23e. The amount ofhydrogen passed through the hydrogen heater and through the variouslines is controlled. In this way the heat of reaction is dissipated inheating the hydrogen, and the temperature of the hydrogenation reactoris controlled at about 400 F. At the bottom of the hydrogenation reactorsubstantially all of the aldehydes have been converted to alcohols butthe olens are not substantially hydrogenated.

The hydrogenation reaction products are removed from the bottom of thetower byline 26 and are passed through the heat exchanger 27 in whichthey are cooled to a temperature of `about 120 F. The cooledhydrogenation products are passed by line 28 to pressure-reducing valve29 where they are reduced from a pressure of about 500 pounds per squareinch to substantially atmospheric pressure. The cooled depressuredhydrogenation products are then passed by line 31 to hydrogen flashtower 32. Hydrogen is removed overhead in this tower by line 33. Thehydrogen which is removed by line 33 is passed out of the system by line34 and may be employed as fuel, or, if desired, the hydrogen can berecycled by line 36, pump 37, and valved line 38 to hydrogen inlet line19.

The hydrogen-free mixture is then removed from the hydrogen flash towerby line 41 and is introduced to water separator 42. A Water fraction isremoved downwardly by line 43. The water fraction is recycled to waterinlet line 8 by means of line 44 which contains circulatory pump 46 andvalve 47. In the event a concentration of impurities such as iron oxidebuilds up in line 44, all or part of the water fraction can bedischarged by valved line 48. When build-up of impurities is a problem,a part of the water is preferably continuously removed from the system.

A fraction containing hydrogenation products is rel moved overhead fromWater separator 42 by line 51 and is passed to separation unit 52. Afraction containing hydrocarbons consisting chiefly of olens is removedin the separation unit by line 53. The hydrocarbon fraction can berecycled to olefin inlet line 4 by means of line than the hydrocarbonsare passed by lines 61 and 62 to additional separating units which arenot shown.

In order to compare results obtained when operating in accordance withthe invention and when operating outside the invention, results obtainedduring two runs in each of a number of periods of hydrogenation arepresented in Table 1 which follows. In these periods hydrogenation wascarried out in a hydrogenation reactor formed by a steel pipe 0.824 inchin inside diameter surrounded by `a jacket containing boiling waterwhich was maintained at 400 F.

The hydrogenation reactor was charged with about 585 milliliters of 1/8inch nickel on kieselguhr catalyst pellets to form a bed about 6 feetlong. The catalyst contained about 44 per cent nickel in its originals-tate or 70 per cent nickel when it was calcined at 1000 F. and reducedat The pressure was maintained at 500 pounds per square inch duringthese periods. The charge to each period Was hydroformylation reactionproducts from the same hydroformylation run to which heptenes had beencharged.- The hydroformylation reaction products contained 43.0 per centoxygenated materials which were chiey aldehydes and 57 per centhydrocarbons which consisted of about per cent oletins. 'Ihe olens inthe charge were thus about 55.2 weight per cent of the charge.

Hydroformylation products were charged to the top of `the hydrogenationreactor. Water, when it was added, was also charged at the top of thereactor. rI`he hydrogenation products were removed from the bottom ofthe hydrogenation unit, depressured, and cooled. A portion ofhydrogenation products from each run was analyzed to determine theamount of unconverted aldehydes in the hydrogenation products. Anotherportion of hydrogenation products from each run was distilled in-to afraction containing all of the oxygenated materials and a hydrocarbonfraction containing unconverted oleins and paraftlns produced by thehydrogenation of the olens. Each oxygenation material fraction was thendistilled into a subfraction containing alcohols and aldehydes and aresidue subtraction. The percent alcohol was then determined bysubtracting the previously determined per cent aldehydes from the totalper cent alcohols and aldehydes in that subtraction. The hydrocarbonfractions were analyzed for olens by determining bromine numbers. In thetable the oxygenated materials, aldehydes, alcohols, residue,hydrocarbons, and olens are all presented as weight per cent of thetotal hydrogenation products.

The eiciency of the retention of oletns in the product stream Wasdetermined by dividing the per cent olen in the charge by lthe per cent`oleiin in the products and multiplying by a hundred. This does not takeinto account the slight change in weight of the hydrogenation productscaused by the addition of hydrogen.

The results of the periods are given in the table which follows. Theweight per cent of olens in the hydrocarbon fraction is given at thebottom of Table 1 to show the extent to which hydrogenation of thehydrocarbon fraction is reduced by operating in accordance with myinvention.

Table 1 FEED RATE AND REACTION CONDITIONS Period 1 Period 2 Period 3 RunRun Run Run Run Run 1 2 1 2 1 2 Water, mls/hr 0 0 100 100 250 250Hydroformylation Products,

mls. r 500 500 500 500 500 500 Hydrogen, Std. Cu. Ft./hr 35 35 35 35 i35 35 Total Pressure, lbs/sq. in 500 500 500 500 500 500 Temperature,Reactor Jacket,

F 400 400 400 400 400 400 Temperature, Hot Zone, F- 405 406 403 404 404404 COMPOSITION OF HYDROGENATION PRODUCTS Oxygenated Materials, Wt.Percent Hydrogenation Productsw 40.0 41.0 43. 0 42.5 42. 5 44.0

Aldehydes, Wt. Percent Hydrogenation Products.. 3.9 3.3 1.6 2.3 3.4 3. 5Alcoholsy Wt. Percent Hydrogcnation Products. 22.1 24.2 33.9 34.2 31.633.5 Residue, Wt. Percent Hydrogenation Pr0ducts- 14.0 13.5 7.5 6.0 7.57.0 Hydrocarbons, Wt. Percent Hydrogenation Products 60.0 59.0 57.0 57.557.5 56.0

Olens, Wt. Percent Hydrogenation Products 31.9 36.9 36.2 39.7 48.8 49.0

sacca-994 A study of the data for the runs in Table l, in which ahydroformylation reaction product charge space velocity of 1.17 wasemployed in each run, shows that the addi- I5 tion of 0.2 liter of waterper liter of hydroformylation products caused an increase in the averageper cent olefins in the hydrocarbon fraction of from 57.7 per cent to66.2 per cent. The addition of 0.5 liter of water per liter ofhydroformylation products further increased the average per cent olensto 86.3 per cent.

The advantages of my invention of preferentially hydrogenating aldehydesin a mixture of aldehydes and olens and producing a hydrocarbon fractionconsisting chiey of olens can be obtained while changing the conditionsof operation described in Table 1. Data from a series of such periodsare given in Table 2 in which hydroformylation products were passed over200 cubic milliliters of a catalyst similar to that used for the runs ofTable 1, but which was somewhat more eiicient for the conversion ofalcohols. In these periods a hydroformylation products charge spacevelocity of 0.5 and a liquid volume ratio of water to hydroformylationproducts charged of0.5 :l were used. The charge and the products wereanalyzed in the same manner used for determining them in the periodsreported in Table l. Table 2 is as follows:

Table 2 COMPOSITION OF HYDROFORMYLATION PRODUCTS CHARGED TO THEHYDROGENATION STAGE FEED RATE AND REACTION CONDITIONS Water, mls/hr 5050 Hydroformylation Products, mls/hr. 100 100 Hydrogen, Std. Cu. Ft./hr3.2 3. 2 Total Pressure, lbs/sq. in 500 500 Temperature, Reactor Jacket,F 365 385 Temperature, Hot Zone, F 375 395-405 COMPOSITION OFHYDROGENATION PRODUCTS Oxygenated Materials Wt. Percent HydrogenationProducts 54. 52. 5

Aldehydes, 'W Percent Hydrogenatlon Products 3. 4 1. 2 Alcohols, Wt.Percent Hydrogenatlon Products 39. 1 44. 8 Residue, Wt. PercentHydrogenation Produ s 11.5 6. 5 Hydrocarbons, W t. Percent HydrogenationProducts 46. 0 47. 5 Olens, Wt. Percent Hydrogenation Products. 37. 441. 5

OLEFIN RETENTION EFFICIENCY Olelns Not Converted to Paratlns, Percent87. 7 97. l

OLEFIN DISTRIBUTION IN HYDROCARB ON FRACTION Olens in HydrocarbonFraction, Wt. Percent. 81. 2 87. 2

The advantages of my invention of preferentially hydrogenating aldehydesin a mixture of aldehydes and olens .sultsfare obtained withhydrogenation temperatures below :4509.11., such as 300 to 450 F., orparticularly 350 to f400 \F.,'and'with nckel, cobalt, nickel tungstensulde, co-

balt molybdate, and copper chromite catalysts. The liquid volume ratios.of Waterto hydroformylation products in the range of'OLlSzl to 2:1 givegood results; preferred results being obtainediwithratios in the rangeof 0.20:1 to

40.5:1 liquid lvolume ratio My invention has the additional advantagethat by employing it in connection with a hydroformylation stage astream of olens can be recovered from the hydrogenation stage which isricher in non-terminal bond oleiins than the stream originallyintroduced to the hydroformylation stage. This occurs because the streamof oleiins recovered from the hydroformylatiou stage is richer innon-terminal bond olens than the stream introduced to it and becausewhen the hydroformylation stage products are hydrogenated in accordancewith the process of my invention, aldehydes are preferentiallyhydrogenated and the hydrocarbons in the hydrogenation stage productsare chiefly olefins.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

I claim:

l. A process for preferentially hydrogenating aldehydes in a mixture ofaldehydes and oleiins which comprises 'hydrogenating said mixture in thepresence of added water in a liquid volume ratio of water to the mixtureof aldehydes and oleins of from about 0.15 :1 to about 2:1, over a lowtemperature hydrogenation catalyst at a temperature of about 300 to 500F.

2. A process for preferentially hydrogenating aldehydes in a mixture ofaldehydes and oleiins which comprises hydrogenating said mixture in thepresence of added water in a liquid volume ratio of water to the mixtureof aldehydes and olefins of from about 0.1511 to about 2:1 over a nickelcatalyst at a temperature of about 300 to about 500 F.

3. A process for preferentially hydrogenating aldehydes in a mixture ofaldehydes and olens which comprises hydrogenating said mixture in thepresence of added water in a liquid volume ratio of water to the mixtureof aldehydes and olens of from about 0.15 :l to about 2:1 over a cobaltcatalyst at a temperature of about 300 to about 500 F.

4. A process for preferentially hydrogenating aldehydes in a mixture ofaldehydes and oleiins which comprises hydrogenating said mixture in thepresence of added water in a liquid volume ratio of water to the mixtureof aldehydes and olefins of from about 0.15:1 to about 2:1 over a nickeltungsten sulde catalyst at a temperature of about 300 to about 500 F.

5. A process for preferentially hydrogenating aldehydes in a mixture ofaldehydes and oleiins which comprises hydrogenating said mixture in thepresence of added water in a liquid volume ratio of Water to the mixtureof aldehydes and oleiins of from about 0.15:1 to about 2:1 over a cobaltmolybdate catalyst at a temperature of about 300 to about 500 F.

6. A process for preferentially hydrogenating aldehydes in a mixture ofaldehydes and oleiins which comprises hydrogenating said mixture in thepresence of added Water in a liquid volume ratio of water to the mixtureof aldehydes and olens of from about 0.15 :1 to about 2:1 over a copperchromite catalyst at a temperature of about 300 to about 500 F.

7. A process for preferentially hydrogenating aldehydes 2,205,184Woodhouse June 18, 1940 in hydroformylation products from ahydroformylation 2,359,759 Hebbard et a1. Oct. 10, 1944 stage whichcomprises introducing water into said'mixture 2,379,670 'Welling et a1July 3, 1945 in a liquid volume ratio of water to hydroformylation"2,511,453 Barry June 13, 1950 products of about 0.2: 1 to 0.5: 1,flowing hydrogen and the 5 2,543,038 v McGrath Feb. 27, 1951 resultingmixture of Water and hydroformylation products 2,636,903 MertzweillerApr. 28, 1953 at a temperature of about 350 to about 400 F, through2,647,149 Condit et al. July 28, 1953 a hydrogenaton zone containingnickel catalyst, removing the resulting hydrogenation products,separating olens FOREIGN PATENTS from said resulting hydrogenationproducts, and recycling 10 493,380 Belgium Oct- 14, 1950 said olens tosaid hydroformylation stage.

References Cited in the le of this patent UNITED STATES PATENTS p1,724,761 Holden Aug. 13, 1929 A11'5-

1. A PROCESS FOR PREFERENTIALLY HYDEOGENATING ALDEHYDES IN A MIXTURE OFALDEHYDES AND OLEFINS WHICH COMPRISES HYDEOGENATING SAID MIXTURE IN THEPRESENCE OF ADDED WATER IN A LIQUID VOLUME RATIO OF WATER TO THE MIXTUREOF ALDEHYDES AND LEFINS OF FROM ABOUT 0.15:1 TO ABOUR 2:1, OVER